What’s a Foot Candle and why does it matter?

By: Rose Southwell

Foot-candle: a unit of illuminance or illumination, equivalent to the illumination produced by a source of one candle at a distance of one foot and equal to one lumen incident per square foot. Abbreviation: FC

Foot-candle (FC) readings are one of the ways our lighting design specialists and project managers measure and quantify light levels in specific commerical or industrial spaces.

By using Footcandles we’re able to measurably demonstrate the existing light levels in a space and compare those to the expected and actual light levels in a newly designed or proposed lighting solution.

How do we increase or decrease light levels in a facility?

Our energy consultants and lighting design specialists perform an on-site audit of your facility, we use 3D lighting design and modeling software to build out a replica of your space from the information gathered during this audit. We use this as a digital blueprint to test and propose more efficient fixtures that meet or exceed (when appropriate) your light level requirements. This complex tool is one of the ways we ensure our designs generate targeted light levels that meet your building’s specific needs.

Using photometric imagery we can compare current light levels to our new design measuring and directing light, adjusting the optics as necessary to deliver the right amount of light to the right areas.

In the photometric images below red indicates higher light levels and FC readings where blue is the low end of the FootCandle reading spectrum.

Light levels at this large industrial facility were well below the minimum and were expensive to run with 1000 watt Metal Halide fixtures – Average Footcandles at 5-19
Same facility light level readings after our LED design – Avg 325% increase to light levels. Bringing site up to IES standards with Footcandles between 48 – 81FC (area needs dependent).

We use the Illuminating Engineering Society (IES) guidelines as a standard for appropriate light levels. IES is an industry-backed, “Lighting Authority” that establishes new construction light level standards and OHSA light level standards for a range of commercial and industrial workspaces and environments. View the Footcandle Lighting Guide for your industry and spaces.